An air intake filter functions to remove particulate matter from the air channel to the intake manifold of a motor vehicle. A variety of filter shapes have evolved over time for this purpose, e.g., flat panel, ring, cylindrical and frustoconical (section of a cone) designs. A popular aftermarket frustoconical design, marketed by the assignee, Advanced Flow Engineering, Inc. (“AFE”) of this application is shown in the digital photograph attached to the Information Disclosure Statement (“IDS”). This filter is removably mounted on an annular seat formed on the upstream end of an adaptor which joints the inside 5½″ diameter of the downstream end of the filter to a 3½″ vehicle air intake tube. A series of decreasing internal angles forms the transition between the larger upstream and smaller downstream bores.
While prior art filters have largely served the purpose of removing particulate matter, such as dirt or debris, from the air entering the air intake manifold, albeit some better than others. Such filters provide little help in preventing evaporative emissions from the intake manifold from entering the atmosphere. Such emissions are a particular problem when the engine is turned off and the intake manifold is hot. This source of air pollution has received considerable attention from the federal and state governments with the goal of reducing such emissions.
To that end, the California Air Resources Board (“CARB”) which effectively sets the maximum air pollution exhaust standards for all motor vehicles sold by original equipment manufacturers (“OEM's) in the United States has recently passed a regulation which requires that a hydrocarbon trap filter be connected in series with the air intake of most motor vehicle internal combustion engines. In addition to a carbon trap filter an air filter of conventional construction is necessary to remove particulate material, such as dirt or debris, often present in the air available which if not removed can cause substantial damages to the engine components.
Prior art designs of such a combination carbon/trap air filter has resulted in a flat-panel hydrocarbon trap filter relatively permanently secured to a downstream section of a conventional OEM closed air box, to inhibit tampering, with a conventional flat panel air filter releasably secured to an upstream section of the closed air box. One such an arrangement, manufactured by Toyota Motor Company, is shown in the digital photograph, labeled stock dual filter assembly, identified in and attached to the information disclosure statement (“IDS”) submitted herewith.
This prior art dual filter assembly is very flow restrictive and as a result engine performance is compromised. There is a need for a more efficient filter arrangement which maintains the tamper resistant characteristics of the OEM carbon trap filter while enhancing the flow of air though the combination filter thereby increasing engine efficiency.